CZ294151B6 - Relay valve for airbrake systems in railway vehicles - Google Patents

Abstract

In the present invention, there is disclosed a relay valve for airbrake systems in railway vehicles wherein the relay valve is characterized in that it has a piston system (20) comprising the following elements on a piston rod (68): a first piston (22) that is arranged in a first cylinder (32) in such a way that the cylinder (32) is divided into two chambers (42, 44), whereby the first chamber (42) is provided on one side of the first piston (22) with a first connection to an active chamber (5) and the second pressure chamber (44) is provided with a second connection via a bore (60) with control pressure, whereby a second piston (24) is arranged in a second cylinder (34) and separates it , into two chambers (62, 64) that are connectable with each another through bore holes (60, 60') with control pressure and through second bore holes (70) with atmosphere (12), whereby a third piston (26) is disposed within a third cylinder (36) the fifth chamber (72) of which lying on the side of the third piston (26) turned away from the second piston (24) is connected with a multiway valve that connects in its one position the fifth chamber (72) with variable pressure, for example with pressure in the active space (5) and in its second position with atmosphere (12).

Description

Relay valve for compressed air brake systems of rail vehicles

Technical field

BACKGROUND OF THE INVENTION 1. Field of the Invention The invention relates to a relay valve for compressed air brake systems of rail vehicles, with an inlet valve for supplying compressed air from a reservoir to the working space and an outlet valve for discharging compressed air from the working space to the environment. It opens the inlet valve when moving in the first direction and opens the outlet valve when moving in the opposite direction.

BACKGROUND OF THE INVENTION

Relay valves are flow rate amplifiers. The inlet and outlet pressures may be of the same size, as well as proportionally or differently, and certain embodiments may have multiple switchable ratios. They are also referred to as pressure transducers or pressure transducers.

The pressure transducers may be combined with control valves which apply control pressure to a single control apparatus, as is evident, for example, from EP-B-0 496 058, the contents of which are incorporated in their entirety in the present application.

Concerning relay valves, pressure transducers as well as their use and incorporation into the compressed-air systems of rail vehicles, reference is made to the guidebook "Brakes for rail vehicles, technical terms and values of brakes, KNORR-Bremse AG, Miinchen, 1990". fully incorporated into the present invention.

The pressure transducer as a special design of the relay valve is, for example, the pressure transducer as well as the pressure transducers DUK 1 .., DUK 3 .., DUK 4 .. from OERLIKONKNORR EISENBAHNTECHNIK AG.

The D D24 pressure transducers contain three pistons, two of which can be disconnected by pneumatic shifting from the inlet and outlet valves. In operating states where these pistons are not disconnected, one of the pistons only enters the inlet and outlet valves when one of the two separate cylindrical spaces is connected to the control pressure.

This arrangement has the disadvantage that the piston system comprises a split piston rod with multiple bearings and seals, requiring costly fabrication and considerable hysteresis in pressure control. Furthermore, this arrangement is disadvantageous in that the pressures set in the operating space, if they are different from the control pressure, cannot be arbitrarily selected by changing the size of the pistons. Finally, these relay valves are disadvantageous in that they exert a retroactive effect on the piston when the piston is connected to the control pressure, thereby creating additional control inaccuracy. Such retroactive effects occur whenever the changeover volume assigned to the control pressure and thus the expansion takes place by means of a switching operation in order to adjust the characteristic of the device. Although the DUK relay valves have one piston rod, they have the disadvantage that, due to the arrangement of the pistons and the resulting compressed air connection, they cannot be set to any pressure with the piston feasible dimensions, and this is generally costly in devices with additional functions.

It is an object of the invention to provide a relay valve for compressed air systems of rail vehicles which overcomes the above-mentioned disadvantages.

-1 CZ 294151 B6

SUMMARY OF THE INVENTION

The principle of the relay valve according to the invention is that the piston system of the relay valve comprises a piston rod with three pistons, the first piston being arranged in the first cylinder and dividing it into two spaces, the first space on one side of the piston containing the first connection with the active space and the second chamber comprises a second connection through the pilot pressure bore, wherein the second piston is arranged in the second cylinder, and divides it into two spaces which are connectable via one pilot pressure bore and the second bore to the environment, the third piston being located in the second cylinder. a third cylinder, the fifth chamber of which is located on the side of the third piston facing away from the second piston, is connected to a multi-way valve which in one position connects the fifth chamber with variable pressure, e.g.

In a preferred embodiment of the relay valve, the boreholes for connecting the third and fourth compartments with the compressed air connection for the control pressure or the environment together are in one housing and according to the desired variant the third compartment is connected to the control pressure and the fourth compartment is connected to the environment or the fourth compartment is connected to control pressure and the third space is connected to the surroundings.

In this way, with otherwise identical constructional arrangements, the resulting forces acting on the second and third pistons can be varied in size and direction, so that the variants differ in that one is suitable for exerting higher output pressures (eg for locomotives) and the other for lower outlet pressures (eg for cars).

In an alternative embodiment of the invention, instead of one compressed air connection to the control pressure, two connections for two control pressures are provided, the second space being connected to the first control pressure and the third space or the fourth space with different control pressure. Thereby, the relay valve can be pre-set by two independent control systems, eg a compressed air control system and an electronic signal processing system with an output pressure achieved electropneumaticly, which is used as the second control pressure.

The invention is described below in relation to the embodiment of the figure.

BRIEF DESCRIPTION OF THE DRAWINGS

1 shows a relay valve according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

The relay valve in Fig. 1 comprises an inlet valve 1 for inlet of compressed air from the reservoir 3 to the chamber 5 as well as an outlet valve 10 for outlet of compressed air from the chamber 5 to the surroundings 12, and a piston system 20 with piston rod 68 and three pistons. with the first piston 22, the second piston 24 and the third piston 26.

The pistons 22, 24, 26 move tightly through a sliding or diaphragm seal in the cylinders assigned to them. Thus, the first piston 22 moves in the first cylinder 32, the second piston 24 in the second cylinder 34, and the third piston 26 in the third cylinder 36. By sealing the pistons 22, 24, 26 in the respective cylindrical spaces, the respective piston spaces 42, 44, 62 are formed. 64, 72.

The relay valve functions as follows:

If control pressure is supplied to the relay valve via bore 60, 60 ', it applies forces to the pistons 22, 24, 26 which, by interconnecting the spaces according to the invention and the compressed air connections, produce certain resultants. With these, the piston system 20 is then moved in the direction of the inlet valve 1 and opens it. Thereby, compressed air flows from the reservoir 3 into the working space 5.

-2GB 294151 B6

With increasing pressure in the operating chamber 5, the pressure on the first piston 22 from the first chamber 42 also increases until a force alignment is achieved on the first piston 22 and the piston system 20 returns to the end position in which both the inlet valve 1 and the outlet valve 10 are. closed.

As the control pressure decreases, the piston system 20 moves to the left, whereupon the outlet valve 10 opens and the pressure in the operative space 5 is reduced by venting through the bore hole 50 until pressure compensation is again achieved on the piston system 20, which leads to the closing position.

Since the force balance affects the pressure set in the working space 5, the following applies:

C - operating pressure 5

Cv - control pressure

Fc - resulting forces that are generated by the pressure of the piston surfaces by pressure C

Fcv - Resulting forces resulting from the loading of piston surfaces by Cv pressure

C / Cv = Fcv / -Fc (Fcv> 0, Fc <0), i.e., the ratio of the pressure in the working space 5 to its control pressure can be influenced as desired by the fact that the piston surfaces assigned to these pressures can be appropriately selected. Here, a distinction is made between the selection of pressures determined by the piston sizes built into the instrument and the ability to switch between different pressures for one instrument with a certain piston size.

First, the effect of the piston sizes built into the apparatus is described.

The pilot pressure reaches the first piston 22 and the second piston 24, which has a different diameter than the first piston 22, by branching bores 60, 60 '. The present description includes both the possibility of loading the second piston 24 from the left from the fourth space 64 and from the right. This selection is achieved by opening or closing the bores 60 'and 70 associated with the spaces 42 and 64, producing the same types of one instrument family.

This embodiment produces an adjusting pressure in the operating space 5 according to the above formula. In order to form the sum of the forces, forces are used, taking into account their signs, taking for example from the left acting force as positive and from the right acting force as negative.

This can be illustrated by examples with the following designations:

A22 piston surface of the first piston 22

A24 piston surface of second piston 24

A26 piston surface of third piston 26

When applying the control pressure in the third space 62 in addition to the second space 44, the following applies:

Fcv = Cv. A22-Cv. A24 (Fcv > 0).

When the control pressure is applied in the fourth space 64 in addition to the second space 44, the following applies:

Fcv = Cv. A22 + Cv. A24-Cv. A26 (Fcv > 0).

For Fc: Fc = -C. A22 (Fc < 0).

It can be seen here that by selecting the size of the pistons 22, 24, 26 and their direction of control pressure loading, any pressure ratios of less than or greater than 1 can be generated.

Pressure ratios relatively close to 1, since small resulting piston forces can be generated by the application of control pressure from the left and right without the use of impractical small pistons.

As a result, the pressure generated in the operating space 5 by this embodiment of the apparatus is predetermined. How the pressure in the operating space 5 of a predetermined device can be switched to another size is also described in connection with Fig. 1.

The process is first determined as described above. The fifth space 72 is connected via the bore 82 to the vent bore 86 so that this space is depressurized. As already explained, the force Fc = -C is manifested. A22 (Fc < 0).

The connection of the bore 82 to the bore 86 is achieved, for example, via the piston 87 of the multi-way valve, which is held in the position shown by the shifting pressure applied through the bore 88. with the working space 5, so that the pressure C acts in addition to the first space 42 in the fifth space 72.

Fc = C. A26-C. A22 (Fc <0)

Thereby, the adjusting pressure ratio C / Cv corresponding to the formula C / Cv = Fcv / -Fc is greater than previously in the vented fifth space 72. The venting and venting of the fifth space 72 can take place in addition to the pneumatic actuated multi-way valve described herein , eg by a solenoid valve.

Derived from the above-described basic variant of the relay valve according to the invention, a variant may be provided wherein the individual branches of bore 60, 60 'and 70 or bore 82 are not associated with said control pressure but with a second control pressure connection for a second control pressure Cv2. With essentially the same effect, there is the possibility of generating the pressure C in the active space 5 in dependence on two control pressures, as described by the equation C = (Cv. Acv + Cv2. Acv2 / Ac, where Ac, Acv and Acv2 are always the sum of piston surfaces pressures C, Cv and Cv2, which have signs with respect to their orientation.

This variant is advantageously applicable if the relay valve is to be set up by two independent systems, for example a single control air pressure system and an electronic signal processing system with an electropneumatic output pressure to be used as the second control pressure.

Claims (4)

1, Relay valve for compressed air brake systems of rail vehicles with an inlet valve (1) for supplying compressed air from the reservoir (3) to the working space (5), with an outlet valve (10) for discharging compressed air from the working space (5) to the surroundings (12), and a piston system (20) which is connected to the inlet valve (1) and the outlet valve (10) by opening the inlet valve (1) when moving in the first direction and opening the outlet valve (1) in the opposite direction 10), characterized in that the piston system (20) comprises on the piston rod (68) a first piston (22) which is arranged in the first cylinder (32) and divides it into two spaces (42, 44), the first space ( 42) on one side of the first piston (22) comprises a first connection with the operative space (5), and a second pressure space (44) comprises a second connection via a bore (60) with pilot pressure, the second piston (24) being arranged in the second cylinder (34); divides it into two spaces (62, 64) which are connectable via a bore (60 ') with control pressure and through a second bore (70) with the environment (12), the third piston (26) being located in the third cylinder (36) having a fifth space (72) lying on the side of the third piston The remote piston (24) is connected by a non-return valve which in one position interconnects the fifth space (72) with a variable pressure, e.g. the pressure in the working space (5) and in the other position with the environment (72). 12). Relay valve according to claim 1, characterized in that the third space (62) is connected via control bores (60 ') to the control pressure, and the fourth space (64) is connected via bore (70) to the environment (12). A relay valve according to claim 1, characterized in that the fourth space (64) is connected via control bores (60 ') to the control pressure, and the third space (62) is connected via bore (70) to the environment (12). The relay valve of claim 1, wherein the second chamber (44) communicates with the first control pressure and the third chamber (62) or the fourth chamber (64) with a different second control pressure.